Omid M. Rouhani

Hybrid meta-heuristic algorithms for solving network design problem

Network design problem has been, and is, an important problem in transportation. Following an earlier effort in designing a meta-heuristic search technique by an ant system, this paper attempts to hybridize this concept with other meta-heuristic concepts such as genetic algorithm, simulated annealing, and tabu search. Seven hybrids have been devised and tested on the network of Sioux Falls. It has been observed that the hybrids are more effective to solve the network design problem than the base ant system. Application of the hybrid containing all four concepts on a real network of a city with over 2 million population has also proved to be more effective than the base network, in the sense of finding better solutions sooner.

Can We Rely on Renewable Energy Sources to Overcome Global Warming

Greenhouse gas emissions, resulting from burning non-renewable energy sources, are recognized as the major cause of global warming. Hence, reducing carbon footprint of energy uses through replacing non-renewable energy sources with renewable ones is believed to be an efficient method for combating climate warming. However, not all renewable energy sources may be appropriate as while they can reduce carbon emissions efficiently, they may be inefficient when it comes to other criteria such as water footprint. For instance, some bio-fuels may consume up to 400 times more water than conventional non-renewable energy sources, which in turn can increase the energy uses of the water sector, resulting in an increased indirect greenhouse gas emissions in long run. This paper discusses that carbon footprint should not be considered as the sole criterion for selecting energy sources. By simultaneous consideration of three different criteria (1- carbon footprint, 2- water footprint, and 3- economic cost), this paper determines the overall efficiency of different non-renewable and renewable energy sources to show how the ranking of energy sources changes when carbon footprint is not considered as the sole criterion for determining efficiency of energy sources for climate change mitigation.

Urban Network Privatization: Example of a Small Network

The majority of recent private facilities are rural highways (outside city boundaries), but privatization of other types of roads could be more beneficial to society. Increasing congestion problems and the existence of transportation modes other than private cars suggest the privatization of urban roads. This study examines the effects of privatization strategies on a simple network with two modes of transportation, such as private cars and buses. With refinement of the general costs of travel, the choice of the links to be privatized, and the enabling policies, a more efficient roadway usage can be achieved. The results from this test network show that (a) in some cases a monopoly ownership performs better than an oligopoly one and (b) privatizing arterials (secondary roads) as well as freeways (primary roads) can lead to lower total costs than privatizing only freeways. This study helps to provide the foundation for more large-scale exploration.

Caspian Sea Negotiation Support System

involving five coastal states of Azerbaijan, Iran, Kazakhstan, Russia, and Turkmenistan. The conflict over the legal status of this multinational water body emerged after the collapse of the Soviet Union. Since then the parties have been negotiating without reaching an agreement on the ownerships of waters, and the oil and natural gas beneath them. Although different division methods have been suggested so far for sharing the Caspian Sea, the gains of the countries from sea area and valuable resources remain unclear as the proposed methods are either focused on the areal shares or on the oil and gas shares. In order to assist the negotiators with reaching a compromise the Caspian Sea Negotiation Support System is developed which allows for simultaneous estimation of ferent legal methods. The developed model is run for different division scenarios to evaluate the sensitivity of the results to the proposed division rules and the Caspian Sea resources values. The results show a high sensitivity of outputs to the proposed division rules and an absence of a direct relationship between the allocated areal and utility shares, suggesting a need for for governing the Caspian Sea. 2694 World Environmental and Water Resources Congress 2010: Challenges of Change.

THE CALIFORNIA RENEWABLE PORTFOLIO STANDARD'S IMPACTS ON THE ELECTRICITY SECTOR IN AN UNCERTAIN COST ENVIRONMENT

According to the Renewable Portfolio Standard (RPS) of California, 33% of the electricity sales must be generated from renewable resources by 2020. The RPS has important implications for electricity consumers, producers, generation units, and the rest of the electricity sector. This paper estimates the effects of implementing the RPS target on electricity prices, greenhouse gas emissions, and portfolios of renewable sources of electricity in different settings. Based on the RPS Calculator, a publicly available model, we built a new model which accounts for uncertainty in prices and generation costs, and demand responsiveness to prices. Without any technology breakthroughs, our model estimates that the average 2020 electricity price in California will be increased to

World Energy Balance Outlook and OPEC Production Capacity: Implications for Global Oil Security

0.166/ kilowatt-hour (kWh) to meet the 33% RPS, 2% higher than the price of the 20% RPS. When conventional fuel prices are high, the 2020 price of producing electricity will not be much different for the 33% RPS target than for the 20% RPS target. And, the main in-state resources to meet 33% RPS will be solar (29%), wind (25%), and geothermal (23%).